Semiconductor device and method for manufacturing the same

ABSTRACT

The semiconductor device  1  comprises a housing  12  which has a recess  24  in the front surface  1 ; a pair of lead electrodes  20  which have the distal ends  34  exposed in the recess  24 , protrude from the external surface of the housing  12 , and are bent along the bottom surface  16  of the housing  12 ; and a semiconductor element  36  which is housed in the recess  24  and is electrically connected to the pair of lead electrodes  20 . The housing  12  has grooves  30  which are formed on the pair of side surfaces  18  which adjoin the front surface  14  and the bottom surface  16  on the right and left sides so as to penetrate the housing  12  from the top surface  28  toward the bottom surface  16  of the housing  12 . The grooves  30  preferably have width substantially equal to the thickness of the lead electrode  20 . The grooves  30  are more preferably formed to be flush with the distal ends  34  of the lead electrode  20.

This application is a Divisional of co-pending application Ser. No.11/700,201, filed on Jan. 31, 2007, the entire contents of which arehereby incorporated by reference and for which priority is claimed under35 U.S.C. §120.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates a light emitting device using asemiconductor light emitting element, and a light receiving device usedin an optical sensor or the like, and, more particularly, to alow-profile light emitting device used as the backlight of a liquidcrystal display.

2. Description of the Related Art

In recent years, the backlight of a liquid crystal display employs asurface-emitting light source comprising a low-profile light emittingdevice and an optical guide which spreads the light emitted by the lightemitting device. One among the light emitting devices used in suchapplications is a low-profile light emitting device comprising a lightemitting diode disposed in a flat housing made of a resin (refer to, forexample, Japanese Unexamined Patent Publication (Kokai) No.2004-363537). The resin housing has such a constitution as a protrusionis provided on an elongated light emitting surface and a recess whichreceives the protrusion is formed on the end face of the optical guide,so as to improve the precision of positioning with respect to theoptical guide.

Japanese Unexamined Patent Publication (Kokai) No. 2004-363537 disclosessuch a constitution as a hanger lead is provided in a part of a leadframe, so as to support the housing on the lead frame during the processof manufacturing the light emitting device. A method of supporting thehousing by using a typical hanger lead will be described below withreference to the accompanying drawing.

FIG. 10(A) shows an example of lead frame 102 having a housing 106.Supported on the lead frame 102 by the hanger lead 100 is the housing106 which has a flat shape and incorporates a pair of lead electrodes104. FIG. 10(B) is a partially enlarged view of the structure ofsupporting the housing 106 by the hanger lead 100. As can be seen fromthis drawing, a distal end 108 of the hanger lead 100 is embedded in aside surface 110 of the housing 106. The housing 106 is supported on thelead frame 102, by forming the support structure comprising the housing106 and the hanger lead 100 on the side surfaces 110 on both sides ofthe housing 106. The housing 106 is supported in such a manner as theprincipal surface thereof is disposed at right angles to the frontsurface of the lead frame 102.

FIGS. 11(A) and 11(B) are perspective views of a light emitting deviceconstituted from the lead frame 102 provided with the housing 106 shownin FIGS. 10(A) and 10(B). A method of forming the light emitting device114 shown in FIG. 11 from the lead frame 102 provided with the housing106 shown in FIGS. 10(A) and 10(B) will now be described.

First, an LED is mounted in a recess 112 of the housing 106. As distalend portions of a pair of lead electrodes 104 are exposed in the recess112, electrical continuity is established in advance between the twodistal end portions and positive or negative electrode of the LED,respectively, by die bonding or wire bonding. The recess 112 is filledwith a translucent resin so as to seal the LED with the resin 116 in thehousing 106. Then the lead frame 102 is cut off along dashed line X. Thelead electrode 104 which is cut off the lead frame 102 is bent along thebottom surface of the housing 106 and is further bent along the sidesurface. During the bending operation, the housing 106 is held in apredetermined posture by the hanger lead 100. Last, the hanger lead 100is bent in the state of supporting the housing 106, and the hanger lead100 is pulled out of the side surface 110 of the housing 106, therebyobtaining the light emitting device 114. As a result, the depression 118in which the distal end portions 108 of the hanger lead 100 wereembedded is left to remain in the side surfaces 110 of the lightemitting device 114 as shown in FIGS. 11(A) and 11(B). The low-profilelight emitting device 114 manufactured in this way is mounted with theside of the lead electrode 104 facing downward. The light emittingdevice 114 is combined with an optical guide with the side of the recess112 serving as the window for light emission, so as to constitute asurface emitting light source for liquid crystal display of mobile phoneor mobile computer.

While the light emitting device disclosed in Japanese Unexamined PatentPublication (Kokai) No. 2004-363537 has a thickness small enough to suitthe application to plane light source, recently there is a demand forlight emitting device of further smaller thickness. However, decreasingthe thickness of the light emitting device having the constitutiondisclosed in Japanese Unexamined Patent Publication (Kokai) No.2004-363537 gives rise to some problems.

For example, when a low-profile light emitting device is manufactured byusing lead frame provided with hanger lead, it is necessary to decreasethe width of the hanger lead which results in a decrease in strength ofthe hanger lead. This increases the possibility of such troubles tooccur as the hanger lead is subjected to torsional deformation when thelead frame provided with hanger lead is transported, thus causing thehousing to tilt. Also during the operation to bend the lead electrode104, stress acting on the housing 106 causes the hanger lead 100 totwist, thus resulting in tilting of the housing 106. Tilting of thehousing makes it impossible to die-bond the semiconductor element, thusgiving rise to the possibility of faulty products.

The low-profile light emitting device is prone to troubles duringpositioning also in case it is mounted by a conventional chip mounter. Achip mounter which is commonly used has a suction nozzle fortransferring the chip. The light emitting device is held on the topsurface thereof by the suction nozzle by means of negative pressure, andis transferred to the mounting position. The light emitting devicetransferred by the suction nozzle is precisely positioned at thepredetermined position of a sub-mount, and is placed at thepredetermined position by breaking the vacuum in the suction nozzle.However, in case the semiconductor device is thinner and lighter inweight than the conventional one, position of the semiconductor devicemay be displaced by a slight movement of air caused by breaking thevacuum, even when the semiconductor device and the sub-mount are alignedprecisely before breaking the vacuum of the suction nozzle.

SUMMARY OF THE INVENTION

Accordingly, an object of the present invention is to provide asemiconductor device of a structure suitable for reduction in thicknessand in weight, particularly to provide a semiconductor device whichallows it to (1) stably hold the housing which is secured onto the leadframe during the manufacturing process, and (2) improve the positioningaccuracy when mounting the product thus manufactured.

The present invention is a semiconductor device comprising a housingwhich has a recess in the front surface thereof, a pair of leadelectrodes which have distal ends exposed in the recess, protrude fromthe external surface of the housing and are bent along the bottomsurface of the housing, and a semiconductor element which is housed inthe recess and is electrically connected to the pair of lead electrodes,wherein the housing has grooves which penetrate the housing from the topsurface toward the bottom surface of the housing and are formed on thepair of side surfaces adjoining the front surface and the bottom surfaceon right and left sides thereof.

The grooves of the semiconductor device preferably have widthsubstantially equal to the thickness of the lead electrode.

It is further preferable that the grooves are formed flush with thedistal end of the lead electrode.

The present invention is a method for manufacturing a light emittingdevice which comprises a housing having a recess in the front surfacethereof, a pair of lead electrodes which have distal ends exposed in therecess, protrude from the external surface of the housing and are bentalong the bottom surface of the housing, and a semiconductor elementwhich is housed in the recess and is electrically connected to the pairof lead electrodes, the method comprising the steps of preparing thelead frame constituted from a metal sheet having a plurality of openingsand a pattern of the lead frame formed therein so as to protrude towardthe inside of each of the openings, exposing the distal ends of the leadelectrode in the recess of the housing and forming the grooves in theside surfaces of the housing by means of circumference of the openingformed in the lead frame, bending the pair of lead electrodes, whichprotrude from the housing, along the external wall surface of thehousing while holding the housing on the lead frame by cutting off thepair of lead electrodes from the lead frame and fitting the openingformed in the lead frame into the groove, and releasing the housing fromthe lead frame.

With the semiconductor device of the present invention, it is madepossible to improve the accuracy of positioning during mounting, too, bytaking advantage of the grooves formed in the side surfaces of thehousing so as to penetrate therethrough. When a guide bar which fits inthe groove is provided on the suction nozzle of the chip mounter whichtransfers the semiconductor device, for example, displacement of thesemiconductor device caused by breaking the vacuum after the transfer ofthe semiconductor device can be suppressed. A guide pin which fits intothe groove may also be provided on the circuit board whereon the deviceis to be mounted. Since the groove penetrates from the top through thebottom, the guide bar or the guide pin can be easily inserted and pulledout either from the top or the bottom. The guide bar and the guide pinmay have simple rod shape. In case the light emitting device is used incombination with an optical component such as optical guide, forexample, the light emitting device and the optical component can beeasily positioned by providing a positioning member at a predeterminedposition of the optical component which fits into the groove of thelight emitting device.

With the semiconductor device described above, in case the groove has awidth substantially equal to the thickness of the lead electrode, theremay a case of supporting the housing by fitting a part of the lead frameinto the groove. Since the groove penetrates from the top through thebottom, the housing can be engaged with the circumference of the openingformed in the lead frame which has higher strength, not on a hanger leadof thin band shape as in the prior art. This enables it to suppress thehousing which is secured onto the lead frame from tilting, even when thelight emitting device is made thinner. At this time, the circumferenceof the opening may be processed so as to match the groove. In case thegroove is not formed flush with the lead frame, for example, thecircumference of the opening may be adjusted in shape so as to achievethe same height as the groove.

It is more preferable to form the groove of the housing flush withdistal end of the lead electrode, namely in the same surface as the mainbody of the lead frame before cutting off the housing, since thiseliminates the need to process the circumference of the opening formedin the lead frame as described above. The housing can be held directlyonto the lead frame by fitting an appropriate portion of thecircumference of the opening formed in the lead frame into the groovewithout processing.

According to the method of manufacturing a semiconductor device of thepresent invention, the housing is secured onto the circumference of theopening formed in the lead frame for manufacturing the semiconductordescribed above, and therefore the housing can be suppressed fromtilting during the manufacturing process. As the portion which has beenholding the lead frame interposed therebetween remains as the groove inthe semiconductor device thus obtained, the groove can be used toprevent displacement during mounting and help alignment with the opticalcomponent. Thus the manufacturing method of the present invention makesit possible to prevent the housing secured onto the lead frame fromtilting and causing defects, and manufacture the semiconductor devicewhich can be easily mounted.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1(A) is a perspective view schematically showing the light emittingdevice of the present invention, and FIG. 1(B) is a partially enlargedview of a part of (A).

FIG. 2 is a perspective view schematically showing the light emittingdevice of the present invention being transferred by a chip mounter.

FIG. 3 is a perspective view schematically showing the light emittingdevice of the present invention mounted on a sub-mount.

FIG. 4 is a top view schematically showing a surface emitting lightsource which combines the light emitting device of the present inventionand an optical guide.

FIG. 5 is a sectional view schematically showing a process ofmanufacturing the lead frame provided with the housing according to thepresent invention.

FIG. 6(A) is a perspective view schematically showing the lead frameprovided with the housing according to the present invention, and FIG.6(B) is a partially enlarged view of a housing support structure of (A).

FIG. 7 is a perspective view schematically showing the lead frameprovided with the housing of the present invention.

FIG. 8 is a top view schematically showing the lead frame provided withthe housing of the present invention.

FIG. 9 is a top view schematically showing a method for decreasing thestrength of the lead frame when removing the light emitting device ofthe present invention from the lead frame.

FIG. 10(A) is a perspective view schematically showing a lead frameprovided with the hanger lead of the prior art, and FIG. 10(B) is apartially enlarged view of a housing support structure of (A).

FIG. 11(A) is a perspective view showing the light emitting device ofthe prior art, and FIG. 11(B) is a partially enlarged view of a sidesurface of (A).

DESCRIPTION OF REFERENCE NUMERALS

-   -   10 Semiconductor device    -   12 Housing    -   14 Front surface of housing    -   16 Bottom surface of housing    -   18 Side surface of housing    -   20 Lead electrode    -   22 Back surface    -   24 Recess of housing    -   28 Top surface of housing    -   30 Groove    -   32 Lead frame    -   34 Distal ends (a, b) of lead electrode    -   36 Semiconductor element    -   40 Opening    -   42 Circumference of opening    -   48 Notch    -   50 Step    -   52 Corner (Edge on top surface side)    -   54 Corner (Edge on bottom surface side)

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The light emitting device 10 shown in FIG. 1 comprises a housing 12 offlat shape and a lead electrode 20 which is bent from a bottom surface16 along a side surface 18 of the housing 12. Front surface of thehousing 12 serves as a light emitting surface 14, with a recess 24formed so as to open in the light emitting surface 14 and extends towardthe back surface 22. The opening of the recess 24 constitutes a windowfor light emission. The recess 24 is filled with a translucent resin 26so as to seal a semiconductor light emitting element (not shown) whichis mounted in the recess 24. A groove 30 is formed in the side surface18 of the housing 12 to extend in parallel to the light emitting surface14. The groove 30 penetrates from the top surface 28 through the bottomsurface 16 of the housing 12. The housing 12 serves as a support memberwhich supports a semiconductor light emitting device and the distal endof the lead electrode 20, and also as a protective member which protectsthe semiconductor light emitting element and the metal wire used in wirebonding from the external environment.

In this specification, the expression of “housing of flat shape” meansthat the housing has a height smaller in comparison to width and depththereof.

The groove 30 is formed flush with the lead electrode 20 which isprovided in the recess 24, as will be described in detail later, and thegroove 30 has a width substantially equal to the thickness of the leadelectrode 20. Therefore in the process of manufacturing the lightemitting device 10, the groove serves as a holding member which holdsthe portion which surrounds the opening formed in the lead frame, namelythe circumference of the opening (referred to as opening circumferencein the present specification), so as to secure the housing 12 withrespect to the lead frame. As a result, the housing can be suppressedfrom tilting when transferring the lead frame provided with the housingand when cutting and forming the lead frame.

The groove 30 can be used in positioning when mounting the lightemitting device by inserting a guide bar or a guide pin into the groove30. Since the groove 30 penetrates from the top through the bottom, theguide bar or the guide pin can be easily inserted and pulled out eitherfrom the top or the bottom of the housing 12. Since the groove 30 opensalso in the side surface 18, such a guide member that enters into thegroove 30 through the side surface 18 can be used, in addition to arod-shaped guide member such as the guide bar or the guide pin. Thuspositioning can be done by means of guide members of various forms,since the light emitting device 10 has the groove 30 which penetratestherethrough. Various methods of positioning will be described below asexamples.

FIG. 2 shows an example of the process of mounting the light emittingdevice 10 by means of the chip mounter. The suction nozzle 120 sucks upthe housing 12 of the light emitting device 10 on the top surface 28thereof, while two guide bars 122 supported by the chip mounter areinserted into the grooves 30 formed in the side surfaces 18 on bothsides of the housing 12. When the guide bars 122 are inserted into thegrooves 30, the light emitting device 10 can be moved up and downsliding along the guide bar 122.

With the light emitting device 10 being guided by the guide bars 122 andpositioned at a predetermined position of the sub-mount, breaking thevacuum in the suction nozzle 120 does not cause the light emittingdevice 10 to be displaced over the surface due to the guide bar, andbeing capable of sliding up and down so as to settle on the sub-mount.As a result, displacement does not occur when vacuum is broken, evenwhen the light emitting device 10 is made with smaller weight andsmaller thickness.

FIG. 3 shows an example of mounting of the light emitting device 10 onthe sub-mount 124. The sub-mount 124 has a guide pin 126 at a positioncorresponding to the position where the light emitting device 10 ismounted. The light emitting device 10 can be prevented from beingdisplaced from the predetermined position over the surface or tiltingfrom the predetermined direction, by fitting the two guide pins 126 inthe grooves 30 formed in the side surfaces 18 located on the right andleft of the light emitting device 10.

Since the groove 30 penetrates the housing 12, the groove 30 and theguide pin 126 can be easily fitted together. That is, after transferringthe light emitting device 10 to a position above the sub-mount 124, itsuffices to align the bottom end of the groove 30 and the top end of theguide pin 126 and lowering the light emitting device 10 verticallytoward the sub-mount 124.

FIG. 4 shows an example of surface emitting light source which combinesthe light emitting device 10 and an optical guide 130. The optical guide130 has two hooks 132 on the end 134. The hooks 132 are formed so as tolock onto the grooves 30 formed in the side surfaces 18 of the housing12, thus enabling it to achieve accurate relative positioning of thelight emitting device 10 and an optical guide 130.

Since the groove 30 penetrates the housing, the light emitting device 10can be positioned easily and accurately simply by aligning the grooves30 and the hooks 132 and inserting the light emitting device 10 betweenthe two hooks 132.

In FIG. 1, it is preferable to form notches or steps in a pair ofcorners (ridges on top surface side) 52 where the top surface 28 and theside surfaces 18 of the housing 12 intersect, so that the top end of thegroove 30 is located below the top surface 28 of the housing 12.

The grooves 30 formed in the side surfaces 18 of the housing 12 areformed at the same time as the housing 12 is molded. At this time, smallburrs 46 tend to be formed on the edges of the groove 30. In case theend of the groove 30 is flush with the top surface 28 of the housing 12,the burrs 46 increase the thickness of the housing 12, and thereforeincrease the thickness of the light emitting device 10. In the case of alow-profile light emitting device, in particular, it is not desirablethat the thickness increases due to the burrs 46. While the burrs 46 maybe removed after being generated, it is not desirable since it increasesthe manufacturing process. When notches or steps (notches 48 are shownin FIG. 1) are formed in the ridges 52 on top surface side so that theburrs generated on the top end of the groove 30 do not protrude beyondthe top surface 28, and therefore it is made possible to prevent theheight of the light emitting device from increasing due to the burrs 46generated on the top end of the groove 30 after the molding process.

It is preferable to form the notches or steps in the pair of corners(ridges on bottom surface side) 54 where the bottom surface 16 and theside surfaces 18 of the housing intersect, so that the bottom end of thegroove 30 is located above the bottom surface 16 of the housing 12. Thelight emitting device 10 of the present invention is mounted with thebottom surface 16 serving as the mounting surface. Therefore, when theburrs 46 generated on the bottom end of the groove 30 protrude beyondthe bottom surface 16, not only the thickness of the light emittingdevice 10 increases but also the burrs 46 touch the mounting substrateand cause displacement in the mounting position of the light emittingdevice 10 and/or tilt the light emitting device 10. By providing thenotches or steps (steps are shown in FIG. 1) in the ridges on bottomsurface side so that the burrs 46 generated on the bottom end of thegroove 30 do not protrude beyond the bottom surface, it is made possibleto prevent such problems from occurring as displacement of the mountingposition of the light emitting device 10 when it is mounted on thecircuit board.

As described above, the light emitting device of the present inventionhas a structure which can improve the mounting accuracy despite smallthickness and small weight. As a result, use of the light emittingdevice in a thin surface emission light source makes it possible tomaintain a high mounting accuracy comparable to that of the lightemitting device of the prior art, even when the thickness of the housingof the semiconductor device of the present invention is decreased to 1.5mm or less. The light emitting device of the present invention may alsobe formed in a shape suitable to a surface emission light source suchthat width of the housing is 3 times as the thickness thereof.

In the light emitting device 10 of the present invention, it ispreferable to fill the recess 24 of the housing 12 with a translucentresin in which case the semiconductor light emitting element secured inthe recess 24 of the housing 12 can be protected from the externalenvironment. In case it is desired to emit light of a color differentfrom that of the semiconductor light emitting element by means of thelight emitting device 10, a fluorescent material may be mixed in thetranslucent resin so as to efficiently convert the wavelength.

The method of manufacturing the light emitting device 10 of the presentinvention will now be described with reference to FIGS. 5 to 9.

First, a metal sheet is punched through and is coated with metallicplating on the surface thereof, to make the lead frame 32. The leadframe 32 has a pair of lead electrodes 20 (20 a and 20 b), of whichdistal ends 34 (34 a, 34 b) oppose each other via a gap. Typically, anumber of pairs of the lead electrodes 20 are formed on one metal sheet.

Then as shown in FIG. 5(A), the lead frame 32 is disposed betweenmolding dies 70, 72 which are separated into upper and lower parts formolding the housing so as interpose the lead frame 32 between the upperand lower molding dies 70, 72. At this time, the distal ends 34 (34 a,34 b) of the pair of lead electrodes 20 and a part of circumference 42of the opening 40 formed in the lead frame 32 are disposed in a cavity62 of the molding dies 70, 72 which has the shape of housing 12.

Then as shown in FIG. 5(B), a molding material 68 is poured into thecavity 62 of the molding dies 70, 72 through a material charging gate 64of the lower molding die 72. The upper molding die 70 has a protrusion66 corresponding to the recess 24 of the housing 12 formed thereon. Whenthe molding material 68 is poured while the protrusion 66 is in contactwith the top surface of distal end 34 of the lead electrode 20, it ismade possible to keep the molding material from being deposited on thetop surface of the distal end 34 and expose the distal end 34 on theinside of the recess 24 of the housing 12.

In this example, the distal ends 34 of the lead electrodes arecompletely exposed on the inside of the recess of the housing 12,however it is not necessary to completely expose these members. Forexample, a part of the lead electrode may be exposed in the recess bydisposing the distal ends 34 of the lead electrodes directly below thebottom of the recess 24 (namely having the distal ends 34 of the leadelectrodes covered by the molding material 68 of the housing 12) andforming a hole in the bottom of the recess 24. Then the light emittingdevice 10 of the present invention can be formed by establishingelectrical continuity between the semiconductor light emitting elementand the lead electrode through the hole.

When the molding material 68 has hardened in the molding dies 70, 72 asshown in FIG. 5(C), the lower molding die 72 is removed as shown in FIG.5(D) and then the upper molding die 70 is removed. When the uppermolding die 70 is removed, the housing 12 can be easily taken out bypushing out release pins 60, which are inserted slidably into the uppermolding die 70, in the direction of P.

Through the series of steps shown in FIG. 5, the lead frame 32 providedwith the housing 12 shown in FIG. 6 is obtained. A part of thecircumference 42 of the opening 40 formed in the lead frame 32 cuts intothe side surfaces 18 of the housing 12 which has been molded, so thatthe penetrating groove 30 is formed. The groove 30 enables the housing12 to be supported on the lead frame 32 throughout the manufacturingprocess of the light emitting device 10. The housing 12 has, on thecircumferential surface thereof, a thin linear ridge-like protrusioncalled the parting line formed along the border of the upper and lowermolding dies.

When the housing is molded by disposing the dies as shown in FIG. 5, theparting line of the housing 12 thus molded and the groove 30 are locatedsubstantially in the same plane.

While a single housing 12 is formed in the case shown in FIG. 6,typically a number (3 in column by 2 in row, totaling 6 in the caseshown) of the housings 12, 12 . . . are formed in one lead frame 32 asshown in FIG. 7. When a number of housings 12 are formed, all thehousings 12 can be formed at the same time by using the molding dies 70,72 which have a number of cavities 62 for the housings and pouring themolding material into the cavities 62 at the same time.

In FIGS. 6 and 7, the process of forming the light emitting device 10 byusing the lead frame 32 provided with the housing 12 will now bedescribed with reference to FIG. 8 and FIG. 9.

First, the inside of the recess 24 of the housing 12 will be describedbelow with reference to FIG. 8.

The housing 12 has a pair of lead electrodes 20 (20 a and 20 b) whichpenetrate from the bottom surface 16 of the housing 12 to the recess 24.Exposed on the inside of the recess 24 are the pair of distal ends 34 ofthe lead electrodes 20 (34 a, 34 b) which oppose each other. Asdescribed above, the housing 12 is supported on the lead frame 32 by thecircumference 42 of the opening 40 formed in the lead frame 32 and thelead electrodes 20.

It is preferable to form the recess 24 of the housing 12 in such a shapethat makes it easier for the light emitted by the semiconductor lightemitting element 36 mounted on the inside of the recess 24 to emerge onthe side of the light emitting surface 14 of the housing 12. Forexample, a tapered shape which gradually expands toward the lightemitting surface 14 is preferably used.

A procedure of securing the semiconductor light emitting element 36 onthe housing 12 will now be described.

The semiconductor light emitting element 36 is die-bonded onto thedistal end 34 a of the lead electrode 20 a in the recess 24 of thehousing 12, then the positive electrode and the negative electrode ofthe semiconductor light emitting element 36 are connected to the distalends 34 a, 34 b of the lead electrodes 20 a, 20 b, respectively, by wirebonding with the metal wire 38. The semiconductor light emitting element36 may be selected from light emitting diodes which emit light ofvarious wavelengths. In order to constitute a surface emission lightsource for white light in combination with an optical guide, inparticular, a nitride semiconductor light emitting element which emitsblue light and a fluorescent material which absorbs blue light and emitsyellow light may be preferably combined.

Then recess 24 of the housing 12 is sealed with the translucent resin 26for the protection of the semiconductor light emitting element 36 fromthe environment. The recess 24 of the housing 12 is filled with thetranslucent resin 26 so as to cover the semiconductor light emittingelement 36 or the metal wire 38, and the resin is hardened.

Then the lead electrodes 20 are cut off from the lead frame 32 at theposition indicated by dashed line X in FIG. 8 and are bent along theexternal wall surface of the housing 12 (called the cut-forming process)thereby to form the connection terminals of J-bend shape. Since the sidesurfaces 18 of the housing 12 are secured onto a part of thecircumference 42 of the opening 40 formed in the lead frame 32, the leadelectrodes 20 can be bent at the same time for the plurality of housings12 formed on one lead frame 32, thus improving the efficiency ofmanufacturing the light emitting device 10. Particularly, according tothe present invention, since the housing 12 is supported by thecircumference 42 of the opening 40 which has a high strength, thehousing 12 can be held in the predetermined posture even when thebending operation applies a stress to the housing 12.

Bending operation of the lead electrodes 20 is carried out by bendingthe narrow portion of the lead electrode 20 either toward the lightemitting surface 14 or toward the back surface 22. Then a portion of thewider portion of the lead electrode 20, which extends beyond the sidesurface 18 of the housing 12, is bent along the side surface 18.

The narrow portion of the lead electrode 20 is preferably bent towardthe back surface 22 as in the light emitting surface 14 shown in FIG. 1,for roughly two reasons described below.

The first reason is the effect of suppressing solder or eutectic layerfrom spreading onto the light emitting surface 14 when mounting thelight emitting device 10. In the light emitting device 10 of the presentinvention, the bottom surface 16 is used as a mounting surface and thelead electrode 20 is electrically connected to the circuit board bymeans of solder or eutectic layer. Therefore, when the lead electrode 20is bent toward the light emitting surface 14, solder bump or eutecticlayer is located near the light emitting surface 14. Thus in case theaccuracy of mounting is not proper and too much solder or molteneutectic metal is applied, the solder or eutectic metal may spread ontothe light emitting surface 14. When the lead electrode 20 is bent towardthe back surface 22, the light emitting device 10 which has been mountedis less likely to be adversely affected and the rate of defectoccurrence can be decreased.

The second reason is the heat dissipation from the light emitting device10. The housing 12 has smaller thickness in a portion where the leadelectrodes 20 are disposed, thus keeping the thickness of the lightemitting device 10 from increasing due to the addition of the leadelectrode 20. While heat dissipation from the light emitting device 10can be improved by increasing the surface area of the lead electrode 20,it requires it to increase the area of the portion of the housing wherethe thickness is made smaller. When the lead electrode 20 is bent towardthe light emitting surface 14, since the area of the portion of thehousing where the thickness is made smaller is restricted by the openingof the window of light emission, it is difficult to increase the surfacearea of the lead electrode 20. When the lead electrode 20 is bent towardthe back surface 22, in contrast, limitation on the surface area of theportion of the housing of smaller thickness is eliminated. Accordingly,surface area of the lead electrode 20 can be increased as long as thepair of lead electrodes 20 are prevented from touching each other,thereby improving the heat dissipation.

When the lead electrodes 20 have been bent, the housing 12 is removedfrom the lead frame 32. In the case of the housing supported by thehanger lead of the prior art (refer to FIG. 10), the hanger lead 100which is formed in a band shape has low strength and can be easily bent.However, the circumference 42 of the opening 40 formed in the lead frame32 whereon the housing 12 is supported in the present invention has ahigh strength and cannot be directly bent. Accordingly, in the presentinvention, strength of the circumference 42 of the opening 40 isdecreased by cutting out the portion near the circumference 42 beforeremoving the housing 12. FIG. 9 shows an example of the cutting outoperation.

In FIG. 9(A) and FIG. 9(B), the circumference 42 of the opening 40 whichsupport the housing 12 is left to remain in a band or L shape afterforming a cutout 44 of the lead frame 32. By cutting out in this way,the circumference 42 of the opening 40 is formed in a configurationsimilar to that of the hanger lead 100 shown in FIG. 10, and can beeasily bent.

As another form, the circumference 42 of the opening 40 may be left inthe shape of rectangular opening as shown in FIG. 9(C). In this form,the housing 12 may be removed by pulling the circumference 42 in thedirection indicated by the arrow, thereby easily deforming thecircumference 42.

The light emitting device 10 made as described above is prone to lessdefects which would be caused by the reduction in thickness and weight,and can be handled easily during the manufacturing process and mountingon the sub-mount.

Components of the light emitting device 10 will now be described indetail.

(Lead Electrode 20)

While there is no restriction on the material used to form the leadelectrode 20 as long as it has electrical conductivity, it is preferableto use iron, steel, copper-clad iron, copper-clad tin, copper, gold,silver-plated aluminum, iron, copper or the like.

(Housing 12)

The housing 12 may be formed from a thermoplastic resin such as liquidcrystal polymer, polyphthalamide resin or polybutylene phthalate (PBT).It is particularly preferable to use a semi-crystalline polymer resinwhich includes crystal having a high melting point such aspolyphthalamide resin, for the reason of high surface energy and goodbonding with the translucent resin 26 which fills in the recess of thehousing 12. Use of this material suppresses the housing and thetranslucent resin 26 from being separated along the interfacetherebetween when the translucent resin 26 is cooled so as to harden. Awhite pigment such as titanium oxide may be added to the moldingmaterial so that the housing 12 can efficiently reflect the lightemitted by the semiconductor light emitting element 36.

(Metal Wire 38)

The metal wire 38 used in wire bonding may be made of, for example, ametal such as gold, copper, platinum or aluminum or an alloy thereof.

(Translucent Resin 26)

The translucent resin 26 is preferably one that has high weatherabilitysuch as silicone resin, epoxy resin, urea resin, fluorocarbon resin or ahybrid resin which includes at least one of the former. Instead of thetranslucent resin 26, an inorganic material having light fastness suchas glass or silica gel.

In case a blue light emitting diode and a fluorescent material arecombined to make the light emitting device 10 which emits white light,particles of the fluorescent material may be dispersed in thetranslucent resin 26. For the fluorescent material, a rare earth-basedfluorescent material which absorbs blue light and emits yellow light(for example, YAG fluorescent material) is preferably used.

The semiconductor device of the present invention can be used in adevice which requires an extremely thin light emitting device such asthe backlight of a liquid crystal display.

1. A method for manufacturing a semiconductor device which comprises ahousing which has a recess in the front surface thereof, a pair of leadelectrodes which have distal ends exposed in the recess, protrude fromthe external surface of the housing, and are bent along the bottomsurface of the housing, and a semiconductor element which is housed inthe recess and is electrically connected to the pair of lead electrodes,the method comprising the steps of: preparing the lead frame made from ametal sheet having a plurality of openings and a pattern of leadelectrodes formed therein so as to protrude toward the inside of each ofthe openings; forming the housing in each opening of the lead frame soas to expose the distal ends of the lead electrodes in the recess of thehousing and form grooves in the side surfaces of the housing by means ofthe circumference of the opening; cutting off the pair of leadelectrodes from the lead frame which protrude from the housing andbending the pair of lead electrodes along the external wall surface ofthe housing while holding the housing on the lead frame by fitting thecircumference of the opening into the groove; and releasing the housingfrom the lead frame.
 2. The method for manufacturing a semiconductordevice according to claim 1, wherein notches or steps are formed in thecorners where the top surface and the pair of side surfaces of thehousing intersect, in the step of forming the housing.
 3. The method formanufacturing the semiconductor device according to claim 1, wherein thenotch or the steps are formed in the corners where the bottom surfaceand the pair of side surfaces of the housing intersect, in the step offorming the housing.
 4. The method for manufacturing the semiconductordevice according to claim 1, further comprising the step of die-bondingthe semiconductor element onto the distal end of the lead electrodeexposed in the recess of the housing.
 5. The method for manufacturingthe semiconductor device according to claim 1, further comprising thestep of filling the recess of the housing with a translucent resinbefore the step of cutting off the pair of lead electrodes from the leadframe.
 6. The method for manufacturing the semiconductor deviceaccording to claim 1, wherein the pair of lead electrodes are benttoward a back surface of the semiconductor device in the step of bendingthe pair of lead electrodes.
 7. The method for manufacturing thesemiconductor device according to claim 1, wherein a portion near thecircumference of the opening is cut out before the step of releasing thehousing.
 8. The method for manufacturing the semiconductor deviceaccording to claim 1, the circumference of the opening is cut out beforethe step of releasing the housing so that a portion of the circumferencesupporting the housing remains in a band or L shape.
 9. The method formanufacturing the semiconductor device according to claim 1, thecircumference of the opening is cut out before the step of releasing thehousing so that the circumference remain in the shape of a rectangularopening.
 10. A method for manufacturing a housing support structurewhich comprises a housing having a recess in the front surface thereof,a pair of lead electrodes which have distal ends exposed in the recess,penetrate through the housing and protrude from the external surface ofthe housing, and a lead frame which supports the pair of lead electrodesat predetermined positions, the method comprising the steps of:preparing the lead frame made from a metal sheet having a plurality ofopenings and a pattern of the lead electrodes formed therein so as toprotrude toward the inside of each of the openings; and forming thehousing in each opening of the lead frame so as to expose the leadelectrodes in the recess of the housing and form the grooves in the sidesurface of the housing by means of the circumference of the opening. 11.The method for manufacturing a semiconductor device according to claim10, wherein notches or steps are formed in the corners where the topsurface and the pair of side surfaces of the housing intersect, in thestep of forming the housing.
 12. The method for manufacturing thesemiconductor device according to claim 10, wherein the notch or thesteps are formed in the corners where the bottom surface and the pair ofside surfaces of the housing intersect, in the step of forming thehousing.
 13. A method of manufacturing a housing support structure whichcomprises a housing having a recess in the front surface thereof, a pairof lead electrodes which have distal ends exposed in the recess,penetrate through the housing and protrude from the external surface ofthe housing, and a lead frame which supports the pair of lead electrodesat predetermined positions, the method comprising the steps of:preparing the lead frame made from a metal sheet having a plurality ofopenings and pattern of the lead electrodes formed therein so as toprotrude toward the inside of each of the openings; and forming thehousing in each opening of the lead frame so as to expose the leadelectrodes in the recess of the housing and secure the housing in twodirections onto a part of the circumference of the opening formed in thelead frame.
 14. The method for manufacturing a semiconductor deviceaccording to claim 13, wherein notches or steps are formed in thecorners where the top surface and the pair of side surfaces of thehousing intersect, in the step of forming the housing.
 15. The methodfor manufacturing the semiconductor device according to claim 13,wherein the notch or the steps are formed in the corners where thebottom surface and the pair of side surfaces of the housing intersect,in the step of forming the housing.